Dielectric composition



Patented Mar." 17, 1942 I UNITED STATES PATENroFF cs nmtno'rnrt i ziiirosrrron Samuel Ruben, New Rochelle, N. Y.

No Drawing. Application September a, 1939,

Serial No. 293,948

scams. 106-191) This invention relates to a composition of matter, particularly plasticized compositions suitable for use as dielectrics and electrical insulating materials.

The general object of the invention is the pro- I vision of a new composition of matter suitable I for use as a dielectric and as an electrical insulator.

A specific object is the provision of an, improved dielectric for electric condensers.

Another object is the provision of an improved dielectric for cables, coils and the like.

\ Still another object is the provision of a di-- electric plasticizer for ethyl cellulose and similar materials.

Other objects wlll be apparent as the disclo- The-dimer is preferably combined with the ethyl cellulose in a common solvent such as xylol and the film cast from a mixture such as a solution, in the manner well known in the art.

The use of the dimer of di-hydronaphthalene as a filmplasticizer appears to be limited to materials with which it is. miscible or which have a common solvent. Thus, the di-hydronaphthalene dimer may be combined with polystyrene as mentioned in my prior and copending application Serial No. 285,559, filed 20 July, 1939; In the present invention the dimer of di-liydronaphthalene is combined specifically with ethyl cellulose or benzyl cellulose. i

The dimer of di-hydronaphthalene can also be added directly tothe cellulose by heating the two materials together. While the materials will combine in practically all proportions the such as high power factor which, while in the order of 1.3% at normal temperatures, rises to an excessive value when the ethyl cellulose is heated, as when used in an alternating current Ethyl cellulose requires the use of a plasticizer to render it flexible and to permit the material to withstand mechanical handling. plasticizers have been suggested and are now being used, for example, the aromatic esters, but

percentage of dimer .of di-hydronaphthalene used is dependent upon the desired electrical and mechanical characteristics. For use as a dielectricsp'acer in an electrostatic condenser, the

preferred range is from 5% to 50% dimer of dihydi'onaphthalene witha preferred maximum of Above 50%, the cold flow characteristics of the ethyl cellulose-di-hydronaphthalene dimer composition render the material less desirable as a solid or film spacer, although applicable for other purposes.

One reason why the dimer of dl-hydronaphthalene can be used in greater percentages than Various these plasticizers have greater dielectric losses v than the ethyl cellulose base and are not electrically as stable. a e

I have found that-the power factor of ethyl cellulose .and particularly ethyl cellulose fllm, is improved considerably by combining the ethyl cellulose with the dimer polymer of di-hydronaphthalene. Also, the addition of the dimer of di-hydronaphthalene provides a permanent p asticizer for the ethyl cellulose and materially improves the resistance of the film to moisture vapor, as well as greatly improving the electrical characteristics. For example, a film canbe made utilizing as much as 5% by weight of the dimer of di-hydronaphthalene to the ethyl cellulose and provides a very flexible filmand brings about considerable impo power factor with'temperature. H U I tance, it reduces therise' in.-

the commonly used ethyl cellulose plasticizers such as aromatic esters, castor oil and chlorinated hydrocarbons, is that its electrical characteristics are so much superior to that of the ethyl cellulose, that it is advantageous rather than disadvantageous to keep the amount of dimer used at the highest point consistent with good mechanical strength. The dimer of di-hydronaphthalene has a power factor of .O2% compared with 1.3% for ethyl cellulose and has a negligible rise of power factor with temperature. It does not oxidize and does not contain cataphorically or electrolytically active components as do waxes'or acid organic compounds when impregnated into spacers and used in electrostatic condensers at high voltage. 5

- 'While the improved composition .of' matter herein described must contain essentially the combination of ethyl cellulose and the dimer of di-hydronaphthalene, the addition of other ma-' terials is not excluded. Also, while the specification specifically describes the use of a film of ethyl cellulose-di hydronaphthalenedimer, it is obvious that the product can used-in, other;

terms, such as lacquers, cast solids, etc., depending upon the proportions used and the amount of added solvents.

Other polymers of di-hydronaphthalene such as the tetramer will also combine with ethyl cellulose but in generalsuch compositions are not as satisfactory asthe combination of the dimer of di-hydronaphthalene' with ethyl cellulose.

What is claimed is: 4

1. A composition of matter comprising a cellulose derivative of the class consisting of ethyl cellulose and'benzyl cellulose and dimer of dihydronaphthalene. a

2. Adielectric comprising a cellulose derivati ve oi. the'class consisting of ethyl cellulose and benzyl cellulose and dimer of di-hydronaphthalene.

3. A composition of matter comprising a film of a cellulose derivative of the class consisting cellulose 50%to 95%.

6. A composition of matter comprising a cellulose derivative of the class consisting of ethyl cellulose and benzyl cellulose and a polymer of di-hydron'aphthalene.

\7. A composition of matter comprising ethyl cellulose and dimer of di-hydronaphthalene.

8. A dielectric for electric condensers, cables,

coils and the like comprising ethyl cellulose and dimer of di-hydronaphthalene.-

' SAMUEL RUBEN. 

